Multi-channel audio power amplifiers that can drive two or more speakers, each in accordance with a respective audio channel, are commonplace. Audio amplifiers whose output configuration supports a bridge tied load (BTL) are also advantageous for a variety of reasons. A difficulty that arises however in the context of small form factor consumer electronic devices, such as desktop computers, laptop computers, and tablet computers, is that a class D, multi-channel audio amplifier that can drive three input audio channels into three speakers in BTL configurations has a large power transistor count, making it difficult to integrate into a small housing. That task can be met by a brute force technique of three, class D full bridge amplifiers (each having a BTL output), however such a technique may require too many power transistors which would take up too much space and would be cost prohibitive.
A class D audio power amplifier product is available that has four output nodes, and is programmable into several different output configurations, namely a) 2 channels of BTL outputs (driving two speakers), b) 4 channels of single ended outputs (driving four speakers), and c) 2 channels of single ended outputs and 1 channel in a BTL configuration (driving a total of three speakers). That product however does not support an arrangement where three channels can be driven through three BTL outputs into three speakers, respectively.